Method to avoid striae in EUV lithography mirrors

Abstract

A method for manufacturing an EUV lithography element mirror includes sagging a plate of a glass material to produce an EUV mirror blank; and polishing a top face of the EUV mirror blank to produce a polished EUV mirror. A method for manufacturing an EUV lithography element mirror includes grinding a top face of a piece of a glass material; sagging a plate of the glass material over the top face of the piece to produce an EUV mirror blank; and polishing a top face of the EUV mirror blank to produce an EUV polished mirror.

What is claimed is:  
     
       1. A method for manufacturing an EUV lithography element, comprising: 
       sagging a plate of a glass material to produce a blank; and  
       polishing a top face of the blank to produce a finished lithography element;  
       wherein striae planes in the sagged plate of glass material remain substantially parallel to the sagged, curved surface of the lithography element.  
     
     
       2. The method of  claim 1 , wherein the glass material is made by flame hydrolysis. 
     
     
       3. The method of  claim 1 , wherein the glass material comprises an ultra low expansion glass material. 
     
     
       4. The method of  claim 3 , wherein the ultra low expansion glass material has a coefficient of thermal expansion of 0±30 parts per billion per degree Celsius in a temperature range of 5 to 35 degrees Celsius. 
     
     
       5. A method for manufacturing a EUV lithography element, comprising: 
       grinding a top face of a piece of a glass material;  
       sagging a plate of the glass material over the top face of the piece to produce a blank; and  
       polishing a top face of the blank to produce a finished lithography element;  
       wherein striae planes in the sagged plate of glass material remain substantially parallel to the sagged, curved surface of the lithography element.  
     
     
       6. The method of  claim 5 , wherein the glass material is made by flame hydrolysis. 
     
     
       7. The method of  claim 5 , wherein the glass material comprises an ultra low expansion glass material. 
     
     
       8. The method of  claim 5 , wherein the ultra low expansion glass material has a coefficient of thermal expansion of 0±30 parts per billion per degree Celsius in a temperature range of 5 to 35 degrees Celsius. 
     
     
       9. A method for manufacturing a mirror, comprising: 
       sagging a plate of a glass material to produce a mirror blank; and  
       polishing a top face of the mirror blank to produce a finished mirror;  
       wherein striae planes in the sagged plate of glass material remain substantially parallel to the sagged, curved surface of the mirror.  
     
     
       10. The method of  claim 9 , wherein the glass material is made by flame hydrolysis. 
     
     
       11. The method of  claim 9 , wherein the glass material comprises an ultra low expansion glass material. 
     
     
       12. The method of  claim 11 , wherein the ultra low expansion glass material has a coefficient of thermal expansion of 0±30 parts per billion per degree Celsius in a temperature range of 5 to 35 degrees Celsius. 
     
     
       13. A method for manufacturing a mirror, comprising: 
       grinding a top face of a piece of a glass material;  
       sagging a plate of the glass material over the top face of the piece to produce a mirror blank; and  
       polishing a top face of the mirror blank to produce a finished mirror;  
       wherein striae planes in the sagged plate of glass material remain substantially parallel to the sagged, curved surface of the lithography element.  
     
     
       14. The method of  claim 13 , wherein the glass material is made by flame hydrolysis. 
     
     
       15. The method of  claim 13 , wherein the glass material comprises an ultra low expansion glass material. 
     
     
       16. The method of  claim 13 , wherein the ultra low expansion glass material has a coefficient of thermal expansion of 0±30 parts per billion per degree Celsius in a temperature range of 5 to 35 degrees Celsius.